Portable Plants. Still another modification consists of a complete quay-side plant mounted like a travelling crane, so that it can be moved longitudinally along steel rails on the quay-side. This plant is particularly useful where large cargo ships have to be emptied and then allowed to remain at their berth until reloaded with another cargo.
Fig. 22.—Portable Railway Plant in Operation.
Complete plants have also been mounted on railway trucks, the engine and pump in this case being on a second waggon (see Figs. [21], [22]). In such a case the plant has to be mounted very low, and it is necessary to lift from the under-side of the truck to, say, a railway waggon, by means of an adjustable belt or bucket elevator (shown at the extreme left of Fig. [21]).
Many other applications will suggest themselves to the reader, and sufficient has been said to prove that for the handling of wheat the pneumatic system is distinctly flexible and convenient; also, it effects a great saving in labour, which is an important consideration nowadays. “Bushelling,” conveying, and weighing by hand used to cost well over a shilling per ton, which figure was reduced to just over 1½d. per ton by pneumatic conveying; these are pre-war costs in both instances, but the relative saving effected by pneumatic conveying is certainly not less under present conditions.
All the previous remarks also apply to linseed and cotton seed in bulk, maize, oats, and in fact all cereals. Such materials have to be accepted as and when the ships arrive irrespective of convenience, and it is an important advantage of pneumatic conveying that the material can be lifted and discharged in the most convenient position; also, when the barge or ship has departed the same apparatus can be utilized to lift the material from its position in store to the cleaning or grinding plant.
CHAPTER V
PNEUMATIC COAL-HANDLING PLANTS
The writer was directly interested in the erection and installing of one of the first plants installed in this country for the elevation and conveying of coal, and a description of the various details may give a good idea of a complete plant, handling coal on a commercial scale.
The conditions to be complied with are as follows: 20 tons of “slack” per hour, to be raised 90 ft. above canal level or 80 ft. above road level.
The coal is brought alongside the power-house by canal barges of 25 tons capacity, or by tipping steam waggons from the railway sidings, a distance of one mile away. In both cases the coal is required to be elevated into overhead bunkers of 600 tons capacity placed vertically over the boilers.